Sunday, 26 February 2017

Infra Red Illuminators

I have dash cams in my car. Alright so thats no big reveal. However, one thing I have noticed is that when driving at night, the rear facing camera is incapable of recording vehicle details, due to being swamped by their headlights.

My thoughts are that if the camera was supplemented by a powerful infrared illuminator, this would provide sufficient reflected IR to allow the camera to register the details of at least a vehicle close behind. The principle being much the same as using a fill flash on a still camera to bring out detail on an otherwise washed out scene.

So I obtained a cheap IR LED lamp module. This has, I discovered, a CdS photoresistor to turn it on when the light level is low.

Being IR, its not so easy to test as a visible lamp! So, I let the CCD camera in my phone take a look at its output, with the lights off (so activate the sensor)

On the bench, it certainly looks bright! I suspect that the CdS cell will need to be disabled in use, otherwise the headlights of a following vehicle with turn the IR off!

I have also today returned to the big LED message board. Now, theres no way im ever going to get the firmware for this, so my only option is to find out what data it needs to drive its panels, and recreate that using another method. Each of the panels (I think theres six), has ten LED dot matrix arrays, in two rows of five, and each LED dot matrix is an 8x8 array. Each array has identical driver arrangements consisting of several ICs and transistors. There are also other ICs which look to be responsible for the addressing of the arrays and the panels. Luckily, none are custom devices, but are all standard logic devices.

So the fun of reverse engineering one of the display 'cells' to find out the actual circuit, has begun. Already, I know several of the connections between the chips. Its just a case of lots and lots of continuity tests!

Magic Morse!

I mentioned in the last post that I had been looking at a Morse code trainer using Arduino by a chap called Ray Burnett. Well, today I used his code (once i'd worked out how it all went together) to program up one of my Arduino Nanos.

I didnt do that first though. First I programmed the code into the Pro Mini (the one with legs but a duff regulator from yesterday), using it as an exercise in finding the right point to release the reset button! But I then realised that the Pro Mini is 3.3v and the LCD I had knocking about is 5v.

So I instead programmed up Sam's Arduino Uno, and breadboarded the circuit. All seemed to go together nicely, apart from the Words Per Minute control, which didnt seem to want to play. I eventually worked out that this was because I was trying to use the old codes method of a 10K pot, but the new version code uses a process of reading a 'key down' situation to select the Word speed. Once I realised this everything started going nicely.

I couldnt of course monopolize Sam's machine, so I transferred the code yet again, this time to a spare Arduino Nano. One of my stock of 16x2 LCDs was unsoldered, so ideal for this project! All the connections for the Arduino, plus the contrast control pot and the backlight resistor were soldered direct to the LCD pads. A 3.5mm jack socket and a piezo sounder from the junk box, plus a 5mm tricolour LED, completed the electronics

Under test on the bench
But it is no use as a loose jumble on the bench! I needed a box for it, and as luck would have it the remains of an old chinese component tester were kicking about! A bit of filing, and liberal use of hot-melt glue (im now in need of resupply of glue sticks!) and the Magic Morse Machine v.8.0 is now a boxed and complete project!

Magic Morse Trainer v.8.
At some point it could do with a DC socket fitting so it can operate without USB power, and the various leftover holes need covering. I did fit the LCD the wrong way around, but its not a big problem. Incidentally if powered by USB, the Serial Monitor in the Arduino IDE can be used as a display. I have added an extra micro USB socket, just for power (the Arduino has a Mini USB, which is a bit rare these days).

So, not any of the projects I should have been working on! But one completed anyway.

Saturday, 25 February 2017

First tests of Arduino (copy) Pro Mini, and a few other things

Having been rather tied up with work and other non-electronics activities, I found a moment today to finally try out one of the cheap Chinese copy Arduino Pro Mini controllers. These are 'supposed' to be 3.3v, 8MHz, ATmega328 devices.

Initially, first tests, just for supply voltage, went well - it did indeed operate at 3v, and the regulator did indeed produce 3v from a 12v supply... then 2.8v....2.6....2.4.....1.8..... what the heck?

Of course, it had stopped working by this point! Reconnecting a direct Vcc of 3v brought the device back to life - clearly the regulator, or an associated component, didnt like 12v! Hmmm, curious, but not a major issue (I will report it back to the seller and see what they want to do about it!), as the processor still seemed to be running.

Next step then, after taking the trouble to solder the pins on, was to try and program it. Now to do this I have a CP2102 based USB to TTL board, another Chinese cheapo. The serial board is recognised well by the PC. The only trouble is that it doesnt have a DTR line, but the Pro Mini does!

Copy Arduino Pro Mini 3.3v 8MHz & CP2102 USB to TTL
As it happens, it is possible, with a bit of mucking about, to make it program without the DTR line - its a case of holding the Arduino in Reset (with the button pressed) until the very moment the IDE ends compiling and starts programming. Naturally this is somewhat hit and miss! But nonetheless, we managed to upload a new Blink file, and then replace it with the standard Blink file. One thing noted originally is that for a Delay(5000); command, it seemed to light the LED for around 8sec! Were putting this down to inadvertently programming it as having a 16MHz clock, but it might be a peculiarity of the board!

So this Pro Mini has a failed regulator. It might be that one of the caps nearby isnt rated high enough, and it is that which has failed. I will investigate that another time. Either way, I will be more cautious when testing the 2nd one!

I have ordered another USB to TTL converter, same chip, but this time with the DTR line available!

Whilst on the subject of Arduinos, a steady stream of small parts from the Far East has brought to my shores the RCA/Phono connectors needed for the Dew Heater. This is still sat on my shack shelf waiting for its final components. These consist of the Phonos, plus the extra MOSFET driver cards (im going to make this a 3 port controller). I now have everything BUT the extra MOSFETs!

I have also seen an Arduino based project for a Morse trainer magic-morse-on-arduino which looks interesting. It seems to have very few external parts, so I might knock one up and see how it plays.

Shiny Phonos!
Some of the parts that have arrived are not yet of immediate use, mostly SMT PCBs ready for making up various driver and port expander modules (which also await a supply of solder paste!), but some will allow the finalising of a few tasks. One such packet contains wire loops with a 20mm fuse holder on them
Fuse Loop
Clearly not for use 'as is'! The intention of course is that the loop is cut and spliced into the +Ve line of a power cable. The first project that will get one of these is the U3S beacon. Other parts that have arrived to bolster stocks are mono and stereo 3.5mm jack plugs, 2.1mm DC barrel plugs, and a pair of LiPo battery monitor and alarm modules. I promised Bob M1BBV one of these to go with a nice hefty LiFePo battery he has for SOTA

LiPo etc Battery monitor and low voltage alarm
Ive also obtained a 6-way ceramic switch, with the intention of using one of my recently acquired selection of die cast aluminium boxes to build a HF antenna switch.

On a very positive note, I tested the 24V SMPSU yesterday - and survived! Both myself and the PSU lived through the tests, and so it is now mounted into the Clansman 4Ah battery box. The next steps will be to add the DC side fuse holder, the 12v regulator and switch for the fan, and wire the output.

 It will then get a test on-load whilst monitoring the output on the 'scope to see if any additional filtering is needed. I would be most surprised if it wasnt! But this is another project that is at least nearing completion.

I also have to add my thanks to a few members of the Vintage Radio restoration forum for some items that have come my way. First is Graham, from whom I obtained at very reasonable cost five assorted and unmolested die cast boxes. These will prove very useful, with the largest already being eyed up for a possible transverter!

Next up is Jeremy, G8MLK, who had a very large number of mixed miniature coils to dispose of. I jumped in and took a punt on a bag of 100, which gives me a good experimental stock.

Ten of the coils are 465kHz IF transformers - very useful!. There are also around 20 of a single LC tuned circuit in a can, some interesting possibilities for these are forming in my mind!

Another member also provided me, again at a small but reasonable cost, three old books. Now, these are not in great shape, but they are incredibly interesting! One is a 1931 edition of the Admiralty book of Visual Signals (this is also the one in the worst condition), on the fascinating subject of flag and semaphore codes. The other two are volumes I and II of the 1938 Admiralty guides to Wireless Telegraphy. Published as the Royal Navy, and indeed the Maritime services of the world, were finally phasing out the last of the spark transmitters, it gives a fascinating insight into how the Royal Navy's communications equipment was, and the many remaining esoteric practices, on the verge of the Second World War. It was rather a shock to me to find antenna tuning capacitances still measured in 'Jars'

[1 Jar = aprox. 1.2nF]

Thursday, 23 February 2017

Beware - Cheap Soldering Guns

As my regular readers will know (ha! how cocky am I to think I have regular readers?), I get a lot of small parts from the Far East. On the whole, I have few problems, other than the odd small packet getting lost in the post. But recently one purchase has proved to be very disappointing.

Having a need to solder some rather hefty cables and connections, and for jointing boxes made from PCB material, I took a chance on a low cost soldering gun. Now, a soldering gun is little more than a switch, a hefty transformer with a very high current, low voltage secondary winding, and a high resistance but otherwise short circuit loop forming the soldering tip. Not exactly hard to make. This particular one was rated 175W and cost a little over  a tenner (you can see where im taking a chance - compare with a similar Weller machine!), now I never for a moment thought i'd get 175W from it! But did think it would maybe run around 125-130W.

The first thing to note is that what arrived is not even marked as 175W! -

wrong rating - not a good start!
But worse was to come. It is supplied with a two pin plug, which is a pain, but not a big problem. Well, I tried to use it. I thought it was a bit off how it took quite a few seconds until it would actually melt solder! But the real problem came when trying to actually make a soldered joint - you cant!

Put the tip to anything bigger than solder wire, and it loses all its heat and the solder solidifies. Even after well over  a minute in contact with a 2inch square of PCB material the solder still wouldnt melt, let alone flow. The damn thing has just NO heat capacity!

As it happens, I have a 230v mains energy meter. Running at a measly 500mA current draw and a power factor of around 0.6, it became very clear that this is simply not up to the job. The picture below shows my energy meter in Watts mode, with the soldering gun active

Thats 71W its reading there! The peak reading feature of the meter showed at no time did the soldering gun consume above 75W!

So, I have started the necessary case for a refund. No doubt the seller will try and argue for it to be sent back. What? to Hong Kong? 'ave a day 'orf! Sending it back will cost more than it did. I will push for a refund, then this one will eventually end up in the WEEE skip!

Sunday, 19 February 2017

GPS, Arduino,WSPR... and dirt

As I type this, the fingers of my right hand are absolutely filthy. This is because it is nearly spring, and time to get the veg plots dug over ready. Soon, it will be time to sow the veg seeds. It will also be time for long distance walks, SOTA, and playing radio in the field!

Im only at the PC since ive been working on an Arduino based GPS logger. Those readers with a very long memory might recall that in the dim and distant past I was playing with a low cost GPS module and PICs, but didnt get it to function. Well, this time im running it with an Arduino Uno, and some 'test' code for the TinyGPS library.

Serial Monitor data from Arduino GPS tests

After several false starts because other peoples code didnt quite work (I never claimed to have written any code!) I came across a sketch using the TinyGPS library, and specifically the exact same GPS module as mine. Apart from having to swap a couple of wires over, it works just fine.

Cheap VKEL GPS module and Arduino Uno
The next stage with this is to work out how to select just the data I want, and instead feed that to an LCD. Eventually, and after a bit of work to port it to a much smaller Arduino such as a Nano, I intend to add an SD card module, and write the GPS data to a .txt file on an SD card, for later analysis in Google Earth. But that I think will require Sams coding skills!

Another aspect of the shack that might need Sams code help, is the Ultimate 3S. This is working very nicely, but I want to get just a smidge more power! But, crucially, I also want to automatically switch antenna connections! The purpose of this will be to allow me to use one of my station receivers to receive WSPR signals, without having to manually throw the antenna switch when its time to transmit!

Hans Summers informs me that his latest firmware for the U3S, v3.12, can provide me with a pre- and post-delayed PTT signal. This is ideal. It also has an LCD backlight timeout function, which will be very useful for field use to conserve battery power. How exactly im going to flash the microcontroller I dont yet know!

Bernard ON7AN has emailed me with tables of results for a 3x BS170 PA using various supply voltages. It seems it will be very much worth the effort of adding a second voltage regulator to give me a higher supply voltage for the PA, and adding the other two MOSFETs. I also intend to change L1 (the PA choke) for a 10t bifilar transformer, as detailed on the QRPlabs website, as this also much improves the output, both in power and spectral purity.

So the plan for the U3S then is - upgrade firmware to v3.12; add all three BS170s; change L1 for 10t bifilar transformer; add regulator for higher PA voltage; add either a pair of 'dry' contacts for switching an external antenna relay, or add a relay internally plus an extra RF connector for the receiver.

Following my last post, which was a bit of a rant over the number of times I see questions from people who have huge monies tied up in shiney radios but nothing in basic test gear, Steve G7TAO has been Tweeting me, he says I should offer basic equipment kits for sale! It has to be said, if one of the first things anyone getting their license bought was a kit containing  a dummy load, digital multimeter, SWR meter etc, along with a simple to understand fault finding guide, there would be far fewer silly questions asked. Now, im not saying its silly to ask, of course it isnt, as its said there are no 'stupid' questions, but it is silly to ask for help when you havent even done the simplest tests to check your equipment yourself! Now, I would love to be able to offer such kits, but sadly I dont have the sort of ready cash that would allow me to invest in such a thing!

Whilst were on the subject of basic tests, whatever happened to people having wavemeters???

Friday, 10 February 2017


Alright, im having a rant,

Yet again ive just been reading one of the all to common requests for help on a ham radio forum, where the absolute very first question anyone needs to ask to be able to help is 'what happens when you Tx to a dummy load?', and it is invariably answered by 'I dont have a dummy load'  !! WTF!!!

Heres the lowdown - if you have a license to transmit, then you must have the means to check your kit without radiating. Its imperetive that you can tell if a problem is down to the antenna system or the radio. To do that you need a dummy load.

No two ways about it. The most essential item of kit you have after the radio is a dummy load. If you havent got one, then get one!


Tuesday, 7 February 2017

Mobile HF

Yesterday (Sunday) Bob M1BBV came over to the G7MRV QTH to avail himself of my assistance with adjusting his mobile HF antennas. Much fun and hilarity ensued, especially in our efforts to get multiple 'buddipole' type antennas matched in a dipole arrangement atop a fibreglass pole!

It turns out Bob has a problem with the internal grounding on his FT-100D, a well known issue that was dealt with on many sets under warrenty. But its not a difficult fix, so i'll sort that for him when he's next able to come over.

As a result of all this though, I myself am now back on HF mobile. At present im using a magmount, so only my short 20m antenna is safe to use whilst actually moving. But I have replacement 3/8th mounts on order, so will hopefully get the proper roof mount fixed soon.

Saturday, 4 February 2017

In The Shack

A bit of spring cleaning in the shack today, I can now actually see the desk!

It does help that the Theremin is now complete and gone to its owner, and the U3S is complete in its case. This meant I could move it to its final home in the shack on the shelf, wire it up for the shacks main 12v rail, and run a coax patch lead from it to the antenna switch. It has the Small Wonder Labs PSK-20 transceiver on top of it (no cooling issues!),a nd the QLG1 GPS is sat on top of that.

Ive even finally got around to fixing the shacks LED desk lighting!

The rear of the desk is still a rats nest of cables though. I could do with getting another antenna switch - ideally a three or four port one!

Post Casing Test of Ultimate 3S WSPR Beacon

Now that its all boxed up (apart from the QLG1 GPS module), Im running the U3S on 40m WSPR at aprox. 200mW today, as a final 'acceptance' test.

First transmission went out at 11:40 UTC, about seven minutes ago, and was uncalibrated - yet 34 stations around Europe reported my signal!

Later, I might QSY to one of the high WARC bands for a further test. But for the next few hours, i'll be WSPRing on 40m at 23dBm.

Wednesday, 1 February 2017

Ultimate 3S Beacon - Case wiring complete

As well as a few further tests of the Theremin, another project in need of completion is the Ultimate 3S Beacon.

Today, I have completed the internal case wiring, and added the 5V 1A regulator.

Due to the small size and tight tolerances of some parts in this, some of the wiring was a little tricky. The RG-174 coax connecting the RF output up twisted at the board end, and had to be stripped back and redone to relieve the torsion. The 1A 5V regulator is a very simple 7805 based circuit mounted on a small piece of prototyping board atop two self adhesive stand-offs. I found that the bare 7805 ran excessively hot (too hot to keep a finger on for more than a few seconds) so added a heatsink. I also took the time to mark the board with the bands for each LPF, so I can see whats in what slot. Later I will make up a little 'Band Card' to attach to the outside of the case showing this.

As well as the coax, another connection that caused problems was to the 'Edit' button. On testing, it turned out that in the confusion of working on things upside down and back to front, I had wired the buttons up arse about, so had to dismantle and swap the connections over. In doing so, the terminal came out of the damn socket! After refitting this, I then couldnt get the sleeving over the pin!

But, with those issues corrected, it is now working in its nice case. Before putting the lid on, I will measure the remaining space, to see how practical it is to fit a battery pack for truly portable operation. I still need to find a suitable plastic housing for the GPS module.